9A2 Achille’s heel inquiry
06-14-2018, 08:46 AM
#16
Did not realize they were prone to bore scoring...
06-14-2018, 08:47 AM
#17
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06-14-2018, 09:48 AM
#18
Burning Brakes
06-14-2018, 09:53 AM
#19
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06-14-2018, 09:57 AM
#20
Burning Brakes
06-14-2018, 11:34 AM
#22
Rennlist Member
You would think that by now both Rennlist and 6Speed would have been populated with "I am talking with my lawyer" messages if that engine was a disaster. When did the Internet exploded when the IMS became an issue...Wait, it was 2400 modems then. My bad
06-14-2018, 11:55 AM
#23
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Thread Starter
I have a 2015 C2 and religiously warm up properly as a rule of thumb.
Did not realize they were prone to bore scoring...
Did not realize they were prone to bore scoring...
Back to the 9A1, it was significantly improved over the prior M96//M97 in many ways, including the elimination and also the improvement of coolant flow in the far reaches of the engine to improve the management of heat cycles and mitigate bore scoring as was more common an affliction of the M96/M97. The 9A1 also had a change in the cylinder liners. As I understand it there is still some risk with 9A1 scoring in the 997.2, especially with the 3.8 motors and it appeared to afflict more cars in northern climates. The 3.8 was more susceptible because of the thinner cylinder wall and the increase torque of that motor vs. the base motor.
In summary, the issue seems to occur when the engine is driven too hard before the piston and cylinders are sufficiently warmed up. The difference in expansion characteristics between the piston and cylinder seems to be the culprit, and over time, the lower reaches of the cylinder become more oval shaped vs. round resulting in an eventual catastrophic failure, referred to as a d-chunk failure
There are lots of threads on this in the 997 area, but here's one with some good background:
https://rennlist.com/forums/997-foru...1-engines.html
Recommendations for warm up include keeping revs low AND avoiding high torque applications until oil operating temps are reached.
Also keep in mind that Porsche continued to refine the 9A1 moving over to the 991.1 platform, and frankly there's no noise on this forum about it, so perhaps its even less of an already rare issue. I'm not after sounding alarms over here, the point of my thread was to try to ascertain if the 9A2 engine was further refined to eliminate the risk.
06-14-2018, 12:49 PM
#24
From what I've read, bore scoring is a potential in various engines from various manufacturers, not just Porsche.
Back to the 9A1, it was significantly improved over the prior M96//M97 in many ways, including the elimination and also the improvement of coolant flow in the far reaches of the engine to improve the management of heat cycles and mitigate bore scoring as was more common an affliction of the M96/M97. The 9A1 also had a change in the cylinder liners. As I understand it there is still some risk with 9A1 scoring in the 997.2, especially with the 3.8 motors and it appeared to afflict more cars in northern climates. The 3.8 was more susceptible because of the thinner cylinder wall and the increase torque of that motor vs. the base motor.
In summary, the issue seems to occur when the engine is driven too hard before the piston and cylinders are sufficiently warmed up. The difference in expansion characteristics between the piston and cylinder seems to be the culprit, and over time, the lower reaches of the cylinder become more oval shaped vs. round resulting in an eventual catastrophic failure, referred to as a d-chunk failure
There are lots of threads on this in the 997 area, but here's one with some good background:
https://rennlist.com/forums/997-foru...1-engines.html
Recommendations for warm up include keeping revs low AND avoiding high torque applications until oil operating temps are reached.
Also keep in mind that Porsche continued to refine the 9A1 moving over to the 991.1 platform, and frankly there's no noise on this forum about it, so perhaps its even less of an already rare issue. I'm not after sounding alarms over here, the point of my thread was to try to ascertain if the 9A2 engine was further refined to eliminate the risk.
Back to the 9A1, it was significantly improved over the prior M96//M97 in many ways, including the elimination and also the improvement of coolant flow in the far reaches of the engine to improve the management of heat cycles and mitigate bore scoring as was more common an affliction of the M96/M97. The 9A1 also had a change in the cylinder liners. As I understand it there is still some risk with 9A1 scoring in the 997.2, especially with the 3.8 motors and it appeared to afflict more cars in northern climates. The 3.8 was more susceptible because of the thinner cylinder wall and the increase torque of that motor vs. the base motor.
In summary, the issue seems to occur when the engine is driven too hard before the piston and cylinders are sufficiently warmed up. The difference in expansion characteristics between the piston and cylinder seems to be the culprit, and over time, the lower reaches of the cylinder become more oval shaped vs. round resulting in an eventual catastrophic failure, referred to as a d-chunk failure
There are lots of threads on this in the 997 area, but here's one with some good background:
https://rennlist.com/forums/997-foru...1-engines.html
Recommendations for warm up include keeping revs low AND avoiding high torque applications until oil operating temps are reached.
Also keep in mind that Porsche continued to refine the 9A1 moving over to the 991.1 platform, and frankly there's no noise on this forum about it, so perhaps its even less of an already rare issue. I'm not after sounding alarms over here, the point of my thread was to try to ascertain if the 9A2 engine was further refined to eliminate the risk.
06-14-2018, 02:35 PM
#25
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I have 39k miles on my 9A1 and 11k on my 9A2.
No issues with either one of them....and I hammer the crap out of 'em and didn't follow the break-in process.
No issues with either one of them....and I hammer the crap out of 'em and didn't follow the break-in process.
06-14-2018, 03:57 PM
#27
Rennlist Member
The tone and content of Jake's message screams to me that he knew what he was saying would become public and he worded it the way he did for that very reason. So where's the harm?
06-14-2018, 06:13 PM
#28
06-14-2018, 06:44 PM
#29
Didn't even know bore scoring was an issue on the 9A1, and I dont really think that it is. I am sure the 9A2 will be just as solid with minimal issues.
06-14-2018, 06:47 PM
#30
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I all about "Don't Fix it if it Ain't Broke"
otherwise known as "Don't go looking for trouble"
Enough cliches?
otherwise known as "Don't go looking for trouble"
Enough cliches?
